【单选题】听力原文: When the United States Geological Survey makes its annual report on earthquakes, California usually leads the nation in the number of tremors that people, rather than measuring instruments, can ...
A.
A significant earthquake occurs in the United States.
B.
A significant earthquake occurs in the ocean.
C.
A significant earthquake does not kill anybody.
D.
A significant earthquake usually measures over 6.5 on the Richter scale.